1. Field of the Invention
The present invention relates to a light emitting module of a vehicle headlamp in which an LED is used as a light source.
2. Related Art
In recent years, an LED which is excellent in a light emitting efficiency and a power consuming characteristic has often been used as a light source of a vehicle headlamp (for example, see JP-A-2005-044683, pages 4-11, FIG. 6). The vehicle headlamp includes a light emitting module with an LED, a projection lens and a reflecting plane.
As shown in FIG. 13, a light emitted from an LED 11 as a light source is diffused within a range of approximately 180 degrees from a light emitting plane. Accordingly, a light which is not incident on a projection lens 21 is wasteful to cause a low efficiency. Therefore, an optical system shown in FIG. 14 has been proposed as measures for efficiently irradiating the light emitted from the LED in a forward direction (for example, see JP-A-2005-228623, pages 3-4, FIG. 2). More specifically, the light which is not incident on the projection lens 22 provided ahead of the LED 12 is reflected by a bowl-shaped reflecting plane 31 which is provided to cover the light source in a forward direction from a side of the light source, and almost all lights are irradiated in the forward direction.
However, a light emitting plane disclosed in the Patent Document 2 is rotationally symmetrical, and the light source and the projection lens are not proper for forming a light distribution pattern with a cut line. Accordingly, there is a problem in that it is impossible to form a necessary low beam light distribution pattern with the cut line when the optical system is mounted as a vehicle headlamp.